The primary objective is to to develop the work begun under the Phase I contract. The primary objective for Phase I and Phase II is to produce, deploy, and evaluate the effectiveness of a state-of-the-art software application for smart phones (i.e., mobile application), [unreadable]Solar Cell,[unreadable] to support decision-making related to sun protection and exposure by Americans to reduce the risk of developing skin cancer attributable to chronic and severe UV exposure and developing other cancers attributable to vitamin D deficiency.